1. Field of the invention
The present invention relates to a pinchcock having a valve casing which has an inlet, an outlet and a passage connecting the inlet and outlet to each other. A sleeve is arranged in the passage and has a sleeve body of elastic material and which is intended to receive the flow of a medium passing through it from the inlet to the outlet or vice versa. Means are provided for fastening the sleeve body to the valve casing in two fastening regions situated at a distance from one another in the longitudinal direction of the passage. A control space is provided which is bounded by the valve casing and the sleeve body and which, for the purpose of pinching together the sleeve body between the two fastening regions, can be placed under a pressure higher than that of the medium.
2. Description of the Prior Art
A pinchcock of this kind is disclosed in DE-A-26 16 045. This pinchcock has a valve casing through the passage of which a sleeve of elastic material passes. Circumferential holding grooves, which are inwardly open in the radial direction, are provided in the valve casing in the two end regions of said passage. Tensioning rings are inserted into the sleeve for its installation, and are then expanded to fasten the sleeve to the valve casing and for that purpose force parts of the sleeve into the holding grooves. The expansion of the tensioning rings, which in the unstressed state have end regions overlapping one another, viewed in the circumferential direction, until in the stressed state the ends abut each other, can be possible only with special tools, since not only do the tensioning rings have to be expanded but at the same time the sleeve must also be compressed. Dismantling of the tensioning rings, for example in order to replace the sleeve, must also entail similar problems.